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Title: The Dimanganese(II) Site of Bacillus subtilis Class Ib Ribonucleotide Reductase

Class Ib ribonucleotide reductases (RNRs) use a dimanganese-tyrosyl radical cofactor, Mn{sub 2}{sup III}-Y{sm_bullet}, in their homodimeric NrdF ({beta}2) subunit to initiate reduction of ribonucleotides to deoxyribonucleotides. The structure of the Mn{sub 2}{sup II} form of NrdF is an important component in understanding O{sub 2}-mediated formation of the active metallocofactor, a subject of much interest because a unique flavodoxin, NrdI, is required for cofactor assembly. Biochemical studies and sequence alignments suggest that NrdF and NrdI proteins diverge into three phylogenetically distinct groups. The only crystal structure to date of a NrdF with a fully ordered and occupied dimanganese site is that of Escherichia coli Mn{sub 2}{sup II}-NrdF, prototypical of the enzymes from actinobacteria and proteobacteria. Here we report the 1.9 {angstrom} resolution crystal structure of Bacillus subtilis Mn{sub 2}{sup II}-NrdF, representative of the enzymes from a second group, from Bacillus and Staphylococcus. The structures of the metal clusters in the {beta}2 dimer are distinct from those observed in E. coli Mn{sub 2}{sup II}-NrdF. These differences illustrate the key role that solvent molecules and protein residues in the second coordination sphere of the Mn{sub 2}{sup II} cluster play in determining conformations of carboxylate residues at the metal sites and demonstrate that diversemore » coordination geometries are capable of serving as starting points for Mn{sub 2}{sup III}-Y{sm_bullet} cofactor assembly in class Ib RNRs.« less
Authors:
; ; ;  [1] ;  [2]
  1. (MIT)
  2. (
Publication Date:
OSTI Identifier:
1047906
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry-US; Journal Volume: 51; Journal Issue: (18) ; 05, 2012
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
OTHERNIH
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; BACILLUS; BACILLUS SUBTILIS; CRYSTAL STRUCTURE; DIMERS; ENZYMES; ESCHERICHIA COLI; OXIDOREDUCTASES; PROTEINS; RADICALS; RESIDUES; RESOLUTION; SOLVENTS; STAPHYLOCOCCUS